Package org.apache.druid.query.rowsandcols.concrete

Class ColumnHolderRACColumn

  • All Implemented Interfaces:
    Closeable, AutoCloseable, Column
    public class ColumnHolderRACColumn
extends Object
implements Column, Closeable
    Implements a RowsAndColumns column based on a ColumnHolder. There is a bit of an impedence mis-match between these interfaces in that the ColumnHolder gets at the values of a row by using a BaseColumn which in turn hands off to `ColumnValueSelector` to actually build the thing. The ColumnAccessor from RowsAndColumns, however, believes that it can provide effectively direct access to values.

    It would be really good to eventually reach down and interact directly with the columns rather than doing this round-about stuff.

    This implementation is also very bad with Objects and data types, it masterfully avoids almost every optimization that we have in place. This should also be revisited at some point in time.

    • Constructor Detail

      • ColumnHolderRACColumn

        public ColumnHolderRACColumn​(ColumnHolder holder)

    • Method Detail

      • toAccessor

        @Nonnull
public ColumnAccessor toAccessor()
        Description copied from interface: Column
        Returns the column as a ColumnAccessor. Semantically, this would be equivalent to calling Column.as(ColumnAccessor.class). However, being able to implement this interface is part of the explicit contract of implementing this interface, so instead of relying on Column.as(java.lang.Class<? extends T>) which allows for returning null, we define a top-level method that should never return null.
        Specified by:
        toAccessor in interface Column
        Returns:
        a ColumnAccessor representation of the column, this should never return null.

      • as

        @Nullable
public <T> T as​(Class<? extends T> clazz)
        Description copied from interface: Column
        Asks the Column to return itself as a concrete implementation of a specific interface. The interface asked for will tend to be a semantically-meaningful interface. This method allows the calling code to interrogate the Column object about whether it can offer a meaningful optimization of the semantic interface. If a Column cannot do anything specifically optimal for the interface requested, it should return null instead of trying to come up with its own default implementation.
        Specified by:
        as in interface Column
        Type Parameters:
        T - The interface that the calling code wants a concrete implementation of
        Parameters:
        clazz - A class object representing the interface that the calling code wants a concrete implementation of
        Returns:
        A concrete implementation of the interface, or null if there is no meaningful optimization to be had through a local implementation of the interface.

      • getBaseColumn

        public BaseColumn getBaseColumn()